Boiler construction



July 19, 1966 .1. G. MUELLER BOILER CONSTRUCTION 2 SheetsSheet 1 FiledApril 29, 1964 INVENTOR- JOHANNES G. MUELLER Voii$m ATTYs,

July 19, 1966 J, MUELLER 3,261,328

BOILER CONSTRUCTION Filed April 29, 1964 2 Sheets-Sheet 2 A h INVENTORJOHANNES G-MUELLER United States Patent 3,261,328 BOILER CONSTRUCTIONJohannes G. Mueller, Michigan City, Ind., assignor to Weil-McLainCompany, Inc., Michigan City, Ind., a corporation of Indiana Filed Apr.29, 1964, Ser. No. 363,382 Claims. (Cl. 122225) The present inventionrelates to heating equipment and, more specifically, to a boilerconstruction utilizable with forced or natural draft firing. While notso limited in its uses, the present invention finds particularlyadvantageous application in connection with sectional type boilers madeup of a plurality of individual rectangular shaped sections which arefastened together mechanically and which define a firebox locatedcentrally in the lower portion thereof.

In general, this invention is concerned with improvements in theinternal construction of multiple pass boilers which allow for anincrease in the capacity of the boilers, assuming the same sizefireboxes as with previous boiler constructions and assuming the samepressure loss or forced draft loss exists throughout the boilers. Inprevious boiler constructions having multiple passes, a flue gas outlethas been provided in the rear of the boiler and the flue gas flowpattern results in an accumulation of the total flue gas volume in thelast pass before the outlet. Since the same boiler sections are used fora series of boilers, this requires that the cross-sectional area of thelast pass be dimensioned in accordance with the maximum total flue gasvolume for the largest boiler in a series. As

a result, the last pass is oversized for the smallest boiler in theseries, resulting in uneconomical operation thereof due to the slow gasvelocity therethrough.

A primary object of the present invention is to provide improvedinternal construction for boilers resulting in an increase in capacityfor the same size boiler. A related object is to provide improvedinternal construction for boilers which results in automatic, uniformdistribution of flue gas along the entire length of the boiler.Additionally, an object is to provide a more economical boiler.

A more specific object is to provide an improved boiler constructionwherein the flue gas outlet is provided on the top of the boiler nearthe center thereof and adequate turn-around passages are provided atboth the front and rear of the boiler whereby the flue gas flow isdivided into two paths resulting in uniform distribution thereofthroughout the boiler. A consequential object is to provide such animproved boiler construction wherein the cross-sectional area of theflue gas passes may be reduced to one-half the cross-sectional area forcorresponding flue gas passes in previously utilized boiler sections. Itfollows that an object is to provide an improved boiler constructioncharacterized in that the capacity of a boiler having the same fireboxas previous boilers may be doubled, assuming the same pressure loss orforced draft loss throughout the boiler.

A general object of the present invention is to provide a new andimproved sectional boiler wherein the construction thereof facilitatescasting, handling, assembling, shipping and the like. A related objectis to provide a sectional boiler which is more compact and requires lessmaterial for the same boiler output as compared to previous boilers.

Further, a general object is to provide a new and improved sectionalboiler characterized in its increased efliciency of operation.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds, taken in conjunctionwith the drawings, in which:

FIGURE 1 is a perspective view of an erected exem- 'plar'ysectional-type boiler embodying the present inven- Patented July 19,1966 tion wherein parts are broken away to illustrate the internalconstruction details of the boiler;

FIGS. 2, 3 and 4 are front elevated views of the front, intermediate andback sections, respectively, of boiler sections utilizable in FIG. 1which are constructed in accordance with the teachings of the presentinvention;

FIG. 5 is a front elevated view of a modified intermediate section forthe boiler in FIG. 1 which is constructed in accordance with theteachings of the present invention; and

FIG. 6 is a partially cutaway view illustrating the crosssectionalrelationship of two of the boiler sections illustrate-d in FIG. 1 havingsealing interposed therebetween.

While the invention has been described in connection with certainpreferred embodiments, it is to be understood that the invention is'notto be limited to the disclosed embodiments but, on the contrary, theinvention is intended to cover the various modifications and equivalentarrangements included within the spirit and scope of the appendedclaims.

For the purpose of describing a preferred environment for the presentinvention, it is shown embodied in a sectional-type boiler, that is, aboiler unit made up of a plurality of individual rectangular-shapedsections which are fastened together by mechanical devices and whichdefine a firebox located centrally in the lower portion thereof.

Referring to the drawings and more specifically to FIGS. 1-4, asectional-type boiler 10, wherein the present invention is incorporated,is illustrated having the front portion thereof removed. In theillustrated embodiment, rectangular boiler sections 11 are erected so asto define a firebox 12 located centrally thereof in the lowermostportion. For the purpose of firing the boiler, a forced draft typeburner or a natural draft fired burner (not shown) may be mounted inplace on the front of the boiler adjacent the firebox 12. Hot flue gasesare produced by a flame in the firebox and the flue gases pass throughthe boiler to a vertical smoke collar or flue gas outlet 13 which servesto lead the gases to a chimney.

For the purpose of generating steam or supplying heated water to a hotwater system, water is circulated through an internal header 16 andthrough water passages 17 formed by coring the casting for each boilersection. The internal header 16 is formed by connecting upper nippleopenings 18 by slipped nipples 19, and a pipe (not shown) which isconnected to the header extends to the heating system. As will beobserved from a careful examination of FIG. 1, the individual sectionsof the boiler are cast so as to form the water passages 17 within eachindividual section and the firebox 12 is entirely surrounded by suchwater passages, i.e., the firebox is surrounded by water backedsurfaces. Since the firebox is surrounded by water backed surfaces, acombustion chamber is not required as would otherwise be required.Accordingly, this boiler construction allows for reduction in the boilerheight and thus allows for a more compact boiler. This construction alsoreduces heat loss through the bottom of the boiler.

The boiler sections are also constructed so as to provide verticalpassages or uptakes 21 between adjacent boiler sections. For thispurpose, each side of the individual boiler sections is formed so that,when adjacent sections are connected together, vertical uptake passages21 are left between the sections and both sides of the boiler. As willbecome apparent, the uptakes 21 are connected to horizontal fluepassages 22 which in turn are connected to a collector chamberconstructed as horizontalflue galleries 23. In this embodiment, thehorizontal passages 22 and flue galleries 23 are centrally located inthe boiler above the firebox 12.

For transferring heat to the water circulating through the header 16 andthe water passages 17 in the sections of the boiler, the flue gasesproduced in the firebox by natural or forced draft firing are forcedlaterally toward the outer wall of the boiler to pass upwardly betweenthe adjacent boiler section through the vertical uptake passages 21. Asmay be seen by reference to FIG. 1, these uptake passages 21 open intheir lower part to the upper region of the firebox crown 24. Thevertical limits of the uptake passages 21 are defined by the roundedupper corners of the boiler itself, which form turn-around passages 21.These passages 21 are disposed laterally of the horizontal flue passages22 with which they communicate by means of downwardly directedconnecting passages 21" so that the hot flue gases pass from the fireboxto the horizontal passages 22 via the vertical uptakes 21, theturn-around passages 21' and the downwardly directed passages 21". Sincea vertical uptake is formed at each side and between adjacent sectionsof the boiler, the hot flue gases in the firebox are divided into aplurality of individual streams of gases equal in number to the numberof uptakes and these streams of gases flow into the horizontal passages22.

In accordance with a principal feature of the present invention, meansare provided for controlling the flow of flue gases in the uptakepassages 21 so that a uniform distribution of the flue gas along thelength of the boiler is obtained and for controlling the flow of fluegases in the horizontal passages 22 and flue galleries 23 so that twoseparate paths of flue gas flow are provided. More specifically, meansare provided for insuring that all boiler sections contribute equally inthe transfer of heat to the heating surfaces by controlling the flow offlue gases in a pattern such as to provide for optimum heat transfer.

For this purpose, the vertical smoke collar or flue gas outlet 13 issecured to the top of the boiler substantially at or near .the centerthereof for receiving flue gases from the flue galleries 23 (collectorchamber) and directing the gases to a chimney. As may be seen, thevertical outlet 13 is in communication with the flue galleries throughvertical outlet passages 25 formed at the center of the centrallylocated intermediate boiler sections above the flue galleries.

In keeping with the present invention, turn-around passages 26 areprovided at the front and rear of the boiler for connecting thehorizontal passages 22 to the horizontal flue galleries 23. As a result,flue gas flowing in the uptakes 21 will be dispersed into the horizontalpassages 22 wherein it will flow along two separate paths, indicated byarrows 27a and 27b, to opposite ends of the boiler, around theturn-around passages 26, and along the flue galleries 23 to the verticaloutput passages 25 which cooperate with the vertical outlet 13. Due tothe fact that two separate paths of flue gas flow are provided, itfollows that the cross-sectional area of the flue gas passages may bereduced to substantially one-half the cross-sectional area for boilersections wherein only a single path of flue gas flow is provided, i.e.,wherein the outlet is connected to the flue galleries at the rear of theboiler, without reducing the boiler capacity for the same total flue gasvolume. Additionally, assuming the same cross-sectional area for theflue gas passages, the same firebox and the same pressure loss or forceddraft loss through the boiler, it follows that the total flue gas volumemay be doubled resulting in the boiler capacity being substantiallydoubled as compared to boilers having only a single path for flue gasflow. Further, the amount of flue gas flowing along the two paths issubstantially equal so that uniform distribution of flue gas flowautomatically results, i.e., substantially equal amounts of flue gasflow through the various uptake passages 21 throughout the entire lengthof the boiler.

While the boiler sections shown in FIGS. 1-4 have laterally disposedvertical uptakes 21 adjacent theside walls of the boiler for receivingshares of the flue gas produced in the firebox, various other verticaluptake arrangements have been found suitable. One such alternativeuptake arrangement is shown in FIG. 5 wherein laterally disposedvertical uptakes 21 extend vertically above the firebox 12 and thehorizontal passages 22 and galleries 23 are laterally disposed outwardlyfrom the uptakes, the horizontal galleries 23 being disposed adjacentthe side walls of the boiler. It will be seen that the uptakes 21located generally in the central region are connected through turnaroundpassages 21 and downwardly directed passages 21" to the horizontalpassages 22. Additionally, it follows that the horizontal passages 22are connected to the flue gas galleries 23 through turn-around passagesat opposite ends of the boiler (see FIG. 1). In operation, gaseouscombustion products pass up through the vertical uptakes 21, around theturn-around passages 21', down the passages 21" and into the horizontalpassages 22. Once in the horizontal passages 22, the gases pass alongtwo separate paths toward opposite ends of the boiler, around theturn-around passages at opposite ends of the boiler into the horizontalflue galleries 23, and along the flue galleries 23 to the center of theboiler wherein they join in vertical outlet passages 25, provided in theintermediate boiler sections, to which a vertical outlet is secured.

Front and rear sections of the arrangement shown in FIG. 5 have not beenillustrated. However, it will be apparent to those skilled in the artthat such sections will be provided with gas flow passages correspondingto the passages of the front section illustrated in FIG. 5.

In further keeping with the present invention, adjacent sections of theboiler are positively and permanently sealed gastight. Morespecifically, the boiler sections are sealed therebetween such that theinterior of the boiler may be maintained under positive pressure, aswith forced draft firing, without leakage of gas from the boilerinterior into the surrounding space. Such scaling is also important fornatural draft firing since uncontrolled air leakage into the boiler,which might impair uniform flue gas distribution, is eliminatedthroughout the life of the boiler so as to assure high efficiency ofoperation. In carrying out this aspect of the invention, the boilersections are cast with sealing lands 30 provided around the outer edgethereof so as to form a substantially continuous loop around the firebox(see FIGS. 2-5). Preferably, the sealing lands extend around theperiphery of the upper portion of each section and extend laterallyalong the portion of each section which defines the lower surface of thefirebox. With such an arrangement, it will be apparent that the sealinglands are accessible even after the boiler has been assembled.Additionally, these sections are cast with sealing lands 31 centrallyformed about the horizontal passages 22 and flue galleries 23 therebyseparating the various regions of the boiler from one another. When twoof the boiler sections are moved into abutting relationship, the sealinglands thereon will be moved into register so that a seal is providedwhich extends in a continuous loop around the firebox and gas passagesof the boiler.

So as to provide an air and gastight seal between registering lands onadjacent sections of the boiler and thus for the purpose of effectivelysealing between every section of the boiler, the sealing lands aregrooved or channeled for receiving sealing material herein shown as heatresistant flexible rope 35, such as asbestos rope or the like. Acontinuous length of rope is laid in the grooves or channels 36 formedin the sealing lands 30 so that the ends thereof overlap and acontinuous seal is provided around the entire boiler interior.Similarly, a length of rope is laid in the groove 37 of the lands 31. Itis preferred that the asbestos rope should be glued in place in thecurved sealing grooves, using adhesive (see FIG. 6). As will be readilyappreciated, this also facilitates erection of the boiler because theasbestos rope is held in place. To insure that the sealing materialremains intact upon dismantling of the boiler, the adhesive should beapplied only to one side of the asbestos rope in the grooved lands ofone section of the boiler.

In the erection of the boiler shown as exemplary in the drawings, a slipnipple 19 is installed in the upper slip nipple opening 18 of onesection, for example, the front section illustrated in FIG. 2, to formthe internal header 16. Smaller, lower nipple openings 40 are thenconditioned for receipt of lower nipples 41 which are pounded in placeto form a part of the water passage system of the boiler. After theasbestos rope has been placed on the one section, for example, a frontsection as illustrated in FIG. 2, the upper and lower nipple openings ofa second section, for example, an intermediate section as illustrated inFIG. 3, are then pre pared for receiving the nipples. The intermediatesection is then driven against the front section with a heavy mallet orthe like to start the nipples into the lower openings and into the upperports or openings of that section. At this point, draw rods 45 areassembled on the sides of the boiler and the intermediate section isthen connected by means of these draw rods to the front section. Theremaining sections, i.e., intermediate and rear sections, are thenassembled in place following the same sequence of steps.

For insuring a perfect seal between boiler sections, it is desirablethat the grooved or channeled sealing lands constructed in the outerwall of the boiler be fash ioned so that, during the operation ofdrawing the adjacent sections of the boiler together by means of thedraw rods, the asbestos rope in the outer curved sealing groove will becompressed so as to form a relatively denser flue gas impervious beadtoward the inside of the boiler. For this purpose, the meeting lands 30are so formed that when the boiler sections are drawn fully together, tothe position shown in FIG. 6, the gap 50 separating the inside edges 51and 52 of the boiler sections is smaller than the gap 53 separating theouter edges 54 and 55. The draw rods 45, when drawing the adjacentboiler sections together, act to compress the asbestos rope 35 andactually extrude it into the gaps 50 and 53 separating the sections. Byproviding a larger space toward the outside edge of the outer wall ofthe sections, however, the compressed asbestos rope is allowed to escapesomewhat, providing compression relief, while the portion of theasbestos rope toward the inside of the boiler is made denser and gasimpervious.

In view of the foregoing, it will be seen that the invention provides asectional boiler construction with sealing means between sections fullyenclosing the boiler interior, which, due to such sealing, can beoperated with either forced draft or natural draft firing and in whichunder either mode of operation the gaseous products of combustion areuniformly distributed throughout the entire length of the boiler and aredispersed along two separate paths. As a result, the cross-sectionalareas of connecting horizontal passages may be reduced allowing for moreeificient heat transfer so that, with the same total flue gas volume,the boiler has substantially the same capacity. Moreover, thecross-sectional areas may be maintained the same so that the totalvolume of flue gas may be doubled resulting in the boiler capacity beingsubstantially doubled.

I claim as my invention:

1. In a multiple pass boiler adapted to be erected so as to define asealed firebox, the combination which comprises, fully enclosed uptakesdisposed laterally and extending from the firebox vertically adjacentthe side walls of the boiler for receiving shares of the flue gasproduced in the firebox, the uptakes being regular in cross section andextending uninterruptedly from the firebox to the top of the boiler,horizontal passages disposed centrally above said firebox inwardly fromthe uptakes, means connecting said horizontal passages to said uptakes,vertical outlet passages provided centrally at the top of the boilerabove the firebox for receiving flue gas from the horizontal passagesand uptakes, a vertical outlet mounted centrally at the top of theboiler and connected to the outlet passages, and means includingturn-around passages for connecting the horizontal passages to theoutlet passages so that the flue gas flow is divided into two pathscausing substantially equal shares of flue gas to flow through theuptakes.

2. In a multiple pass boiler adapted to be erected so as to define asealed firebox, the combination which comprises, fully enclosed uptakesextending from the firebox vertically for receiving shares of flue gasproduced in the firebox, the uptakes being regular in cross section andextending uninterruptedly from the firebox to the top of the boiler, ahorizontal collector chamber disposed adjacent the side walls of theboiler and extending the length of the boiler for receiving the streamsof flue gas from the uptakes, a vertical flue gas outlet mountedcentrally at the top of the boiler, vertical passages for connecting thecollector chamber to the outlet, means including horizontal passageslaterally disposed outwardly from the uptakes and turn-around passagesat opposite ends of the boiler for connecting the uptakes to thecollector chamber so that substantially equal shares of flue gas flowthrough the uptakes and the flue gas flows to the collector chamber.

3. In a boiler adapted to be erected so as to define a sealed firebox,the combination which comprises, fully enclosed uptakes extending fromthe firebox vertically for receiving shares of flue gas produced in thefirebox, the uptakes being regular in cross section and extendinguninterruptedly from .the firebox to the top of the boiler, a verticalflue gas outlet mounted centrally at the top of the boiler, a horizontalpassage extending the length of the boiler, turn-around passages forconnecting the uptakes to the horizontal passage so that flue gas fromthe uptakes flows into the horizontal passage, a horizontal collectorchamber extending the length of the boiler, turnaround passages atopposite ends of the boiler for connecting the collector chamber to thehorizontal passage so that flue gas from the horizontal passage flowsinto the collector chamber and so that substantially equal shares offlue gas flow through the uptakes, and vertical passages providedcentrally at the top of the boiler for connecting the collector chamberto the outlet.

4. A boiler as defined in claim 3 including a plurality of boilersections, sealing means provided in facing surfaces of adjacent boilersections which register and are formed in continuous loops around theboiler sections so that the interior of the boiler is positively sealedfrom the surrounding atmosphere, and sealing means provided in facingsurfaces of adjacent boiler sections which register and are formed toseal off the forward outlets from the firebox and the uptakes.

5. A boiler as defined in claim 3 wherein said firebox, horizontalpassages, collector chamber and vertical passages are surrounded bywater passages.

References Cited by the Examiner UNITED STATES PATENTS 739,503 9/1903Murphy 122225 X 1,164,061 12/1915 Bechfield 122225 X 1,240,517 9/1917Van Leeuwen et al. 122-225 1,851,453 3/ 1932 Silver 122-225 2,3 16,6034/ 1943 Livar 122225 KENNETH W. SPRAGUE, Primary Examiner.

1. IN A MULTIPLE PASS BOILER ADAPTED TO BE ERECTED SO AS TO DEFINE ASEALED FIREBOX, THE COMBINATION WHICH COMPRISES, FULLY ENCLOSED UPTAKESDISPOSED LATERALLY AND EXTENDING FROM THE FIREBOX VERTICALLY ADJACENTTHE SIDE WALLS OF THE BOILER RECEIVING SHARES OF THE FLUE GAS PRODUCEDIN THE FIREBOX, THE UPTAKES BEING REGULAR IN CROSS SECTION AND EXTENDINGUNINTERRUPTEDLY FROM THE FIREBOX TO THE TOP OF THE BOILER, HORIZONTALPASSAGES DISPOSED CENTRALLY ABOVE SAID FIREBOX INWARDLY FROM THEUPTAKES, MEANS CONNECTING SAID HORIZONTAL PASSAGES TO SAID UPTAKES,VERTICAL OUTLET PASSAGES PROVIDED CENTRALLY AT THE TOP OF THE BOILERABOVE THE FIREBOX FOR RECEIVING FLUE GAS FROM THE HORIZONTAL PASSAGESAND UPTAKES, A VERTICAL OUTLET MOUNTED CENTRALLY AT THE TOP OF THEBOILER AND CONNECTED TO THE OUTLET PASSAGES, AND MEANS INCLUDINGTURN-AROUND PASSAGES FOR CONNECTING THE HORIZONTAL PASSAGES TO THEOUTLET PAS-